This invention relates to an electrical connector for connecting oppositely arranged first and second mating electrical means, comprising a support member, a first circuit having a plurality of electric contact elements arranged on one surface of the support member to contact electric contacts of the first mating electrical means, a second circuit having a plurality of electric contact elements arranged on the other surface of the support member to contact electric contacts of the second mating electrical means, and conductors connecting the first and second circuits, and more particularly to an electrical connector capable of removing solders adhered to electric contact elements from mating electric contacts, while limiting the sliding movement of the mating electric contacts.
In order to inspect the performance of a ball grid array connector having a plurality of electric contacts in the form of a hemispherical protrusion made of solder or the like, a socket connector has been used, which is detachably fitted with the ball grid array connector. In such inspections, the electrical contact between electric contacts of the two connectors amounts often to several thousand times or more. As a result, the solder forming the electric contacts of the ball grid array connector tends to adhere to the electric contact elements of the socket connector, causing defective or failed electrical connection therebetween.
Owing to such an adherence of the solder to the electric contact elements of the socket connector, removal of the adhered solder therefrom is needed by the use of a brush every several hundred times or thousand times of the contact between the electric contacts and the electric contact elements. However, the removal of the adhered solder by brushing is not an easy matter if not impossible. Earlier use of the brush would make it easy to remove the adhered solder. However, it would increase the number of time of the brushing operation, which would also increase the man-hour of the operation of the electrical connector, resulting in increased cost of operation.
There is disclosed in U.S. Pat. No. 5,984,691 an electric contact element of an electrical connector, having the dendritic structure at its surface. According to its explanation the dendritic structure serves only to enhance the electrical connection. The dendritic structure does not contribute to removal of adhered solder on the mating electric contacts.
In the U.S. Pat. No. 5,984,691, there is also disclosed the interposer comprising the support member, apertured members arranged on its upper and lower surfaces and the flexible circuitized substrates further arranged on the upper and lower surfaces of the apertured members and supporting the conductors or electric contact elements. With this construction, when a force is applied to the conductors or electric contact elements, the circuitized substrate is depressed within the aperture of the apertured member. In the preamble of the specification of the U.S. Pat. No. 5,984,691, there are described that when a force is applied to the conductive elastomer elements, the resistivity of such conductive elastomer elements will be varied, that when the flexible circuit is subjected to a cyclic stress, it will shorten the fatigue life of the circuit lines on the flexible circuit, thereby possibly resulting in a failed connection, and that if the various components in the system are poor in compressibility, they could not accommodate their manufacturing tolerances. In order to overcome these problems, the invention of the U.S. Pat. No. 5,984,691 proposed the elastic support member. It is clear, however, that this proposal does not have the purpose of removing adhered solder.
As can be seen from FIG. 1 of the U.S. Pat. No. 5,984,691, electric contacts arranged on the upper and lower surfaces of the support member are similar in shape to one another. However, there is need to change the shapes of the upper and lower contacts in the most suitable manner depending upon the shapes of mating contacts and their applications.
In manufacturing, moreover, it is needed to investigate microstrip lines in consideration of characteristics as transmission lines preferable for measurements. In reality, however, it is very difficult to investigate the microstrip lines.
As described above, there is a hitherto used electrical connector comprising a ball grid array connector (first connector) and a socket connector (second connector) which are brought into detachable abutment against one another to electrically connect a plurality of electric contacts made of solder in the form of a hemispherical protrusion provided on one surface of the first connector and a plurality of electric contact elements provided on one surface of the second connector. In such a construction, the electric contacts of the first connector arranged with an interval of 0.8 mm are as little as about 0.2 mm in diameter. The narrower the interval or pitch of the electric contacts, the narrower will become contacting areas with the mating contact elements. Therefore, a CCD (charge-coupled device) camera is commonly used to bring the electric contacts of the first connector and the electric contact elements of the second connector into alignment with one another.
As shown in FIGS. 10 and 12, the first connector 110 includes a connector plate 111 made of a ceramic or hard resin substrate or board having a rigidity, on one surface of which are provided a plurality of electric contacts 112 of solder (Pb and Sn) in the form of a hemispherical protrusion. These electric contacts 112 are formed by reflow-soldering of solder balls arranged on lands of a hard resin board.
The second connector 120 includes a plurality of electric contact elements 130 adapted to contact the electric contacts 112 of the first connector 110. These electric contact elements 130 are provided on conductors 126 provided on one surface of a substrate 122 or flexible printed board or the like which is formed with slits 124 around the conductors 126, thereby making flexible the parts of the substrate and the conductors surrounded by the slits 124. With this construction, the elastic support of the electric contact elements accommodates any differences in height between the electric contacts 112 of the first connector 110. The electric contact elements 112 are in general treated with a surface treatment such as nickel or gold plating because they are electrically contacting portions.
FIG. 11A illustrates part of such a first connector 110 including four electric contacts, and FIG. 11B shows part of the second connector 120 in opposition to the part of the first connector 110, whose slits 124 are directed in the same direction. FIG. 11C is a cross-sectional view of the part of the second connector 120 shown in FIG. 11B. FIG. 11D schematically illustrates the electric contact elements 130 supported in the cantilevered manner before urged. FIG. 11E schematically illustrates the electric contact elements 130 urged downward by the electric contacts 112. As shown in FIG. 11E, in the case of the arrangement of the slits 124 directed in the same direction, the electric contacts 112 of the first connector 110 are subjected to horizontal direction shown by an arrow A owing to the horizontal components of the reaction forces caused by the parts of the substrate and the conductors surrounded by the slits 124 of the second connector 120, as a result of which the first connector 110 is subjected to the horizontal force shown by the arrow A. Consequently, the distance of the sliding movement of the electric contacts 112 of the first connector 110 increases although the first connector 110 is guided to prevent it from wobbling in the direction A by a plug and socket mechanism.
In the case of 70% or more of the slits 124 directed in the same direction, it would be difficult to restrain the distance of sliding movement of the electric contacts 112 of the first connector 110, so that contacting positions between the electric contacts 112 of the first connector 110 and the electric contact elements 130 of the second connector 120 would irregularly vary, resulting in unstable contact between the electric contacts 112 and the electric contact elements 130.
With the slits 124 in excess of 70% directed in the same direction, the first connector 110 is further moved by the force shown by the arrow A in FIG. 11E in addition to the sliding movement of the electric contacts 112 although the first connector 110 is guided by the plug and socket mechanism. As described above, the range of contact between the electric contacts 112 and the electric contact elements 130 is very narrow, so that the contact therebetween comes out of the range, with the result of defective or failed electrical connection.
If the slits 124 are directed substantially in the same direction, the distance of the sliding movement of the electric contacts on the electric contact elements would excessively increase, causing excess wear of the contacting portions therebetween.